Preparation of rare metallic oxides



5 the like.

Patented July 13, 1926.

UNITED STATES norm ALLEN nanny, or new HAVEN, comvnc'rrcv'r.

PREPARATION OF RARE METALLIC OXIDES.

No Drawing.

In electrical appliances and particularly in incandescent lamps thereare many uses for highly refractory materials, such as the rare metallicoxides, thoria, zirconia, and These oxides have uses in variouselectrical appliances particularly as asso-' eiate'd with refractoryconductors for heating or resistance uses. When usedin a vacuum or inertgas container, preferably in molded form, as in incandescent lamps, Iv

have found that'such metallicoxides, prepared for use in obvious ways,are porous and full of occluded gases detrimental to my purpose,particularly the oxygen content.

When' the metallic oxide is associated with the heating element in alamp bulb, for example, the gases suchas oxygen in the pores of theoxide expand and escape. The oxygen content of the gases thus liberatedhas, at the temperature of operation, a greater atfinity for the metalof the resistor than it has for the elements with which it is combined,and a chemical reaction takes place whereby the oxygen of the gasesfrees itself and combines with the metal of the resistor to form anoxide of that metal. This reaction decreases the cross-section of themetal, increases its resistance, decreases the temperature andgenerallyoperates to defeat the purpose of the desired structure in use.

The use of the rare metallic oxides for lamps is advantageous asresistor illuminants because of their non-conductivity and any localaction in the lamps which tends.

to break-down the oxide and hence decrease the resistance of the same isdeleterious to the lamp operation and efiiciency.

The purpose of this invention is to provide a new and useful method ofpreparing the rare metallic oxides for use in electrical appliances,such as incandescent lamps, a new and useful method of conditioning theoxides in' the lamp or similar appliance for the desired use, and a newand useful product.

The invention will be described as applicable to an incandescentlampstructure as one of its important uses. In this use chemically purezirconia, thoria, or other rare metallic oxide, may be used as anilluminant base. The resistor is associated with the base in the bulb orcontainer to act- Ap'plication filed November 14, 1918. Serial No,262,616.

ing element for the base. The latter, when sufficiently heated as it isby the resistor or heating element, becomes an illuminant. However, theresistor and base, working together in the desired purpose forillumina-.

tion, may act one on the other, due to detrimental gases in the base, todefeat such purpose. This is true-no matter to what possible degree thelamp is evacuated in its manufacture, because the porous base will notgive up its occluded gases under such treatment.

The solution ofthe problem, then, begins with the treatment orpreparation of the base before it goes in the lamp. I start withpowdered zirconia, which I will use as an example, subject it to anintense heat to dehydrate it, then mix the dehydrated powder with atemporary binder, as water, mold it to the shape of the desired base,subject the molded base to heat suflicient to completely drive off thetemporary binder, and

then sinter it under intense heat. So far, the treatment given the baseis particularly important if such base is to be used in an evacuated. orinert gas filled lamp or like appliance.

The base so prepared is now put in a bath the temperature of which ispreferably the boiling point of the substance composing the bath. Suchsubstance should be something in the nature of parafline or solidhydrocarbon. The heat causes the expansion and free exit of all occludedgases, which will then thoroughly be driven out of the base, due to theentrance of the'parafline of higher specific gravity into all the pores,assisted by capillary attraction. The base may now be cooled, preferablywith a sufficient coating to insure it against the entrance of any airdue to the contraction of the paraffine in the pores.

The lamp is now structurally made up in the desired manner with theresistor and base associated for their functional purpose. One eflective way, but not necessary to an understanding of this invention, isshown in my copending application Serial No. 271,352, filed January 16,1919. The lamp is connected to the vacuum. pump and evacuated. Then acurrent is passed through the resistor sufficient to volatilize anddrive off the parafiine from the base. The paraffine is evacuated involatile form by the vacuum pump, During the latter operation the bulbis preferably kept warm to avoid the deposition of the parafiine on theinterior of the bulb.

If the lamp is to be operated with inert gas, the container "is -filledwith such gas' after the paraiiine passes off; otherwise, the lamp orcontainer is sealed tightly in the usual manner.

The base illuminant of rare metallic oxide is now in the desiredcondition for useful operation in the inert gas or vacuum. It is in purecondition and has had treatment to insure it against chemical reactionsbetween it and the resistor with which it is associated.

Thus, I have provided a base to be used as a luminant in my improvedlamp which has the advantageous characteristics of being free of anyaction in the lamps'operation other than intended. The rare metallicoxides, when used in the manner stated, greatly increase the efiiciencyof lamps in the art of electric lighting.

I claim as my invention:

1. The method of preparing a porous body of highly refractory materialfor use in electrical appliances, which consists in subjecting the bodyto heat in the presence of a molten substance solid at normaltemperatures, until the ases in the pores have been replaced by saimolten substance, allowing the body to cool and said substance tosolidify in the pores thereof, incorporating the same in a container,volatilizing the substance fillin the pores, and simultaneouslyevacuating t e container.

2. The method of preparing a porous body. of hi hly refractory materialfor use in electrica appliances which consists in removing the occludedgases therefrom, filling the pores with a material solid at ordinarytemperatures but capable of being volatilized, incorporating the same inthe appliance and then removing the material filling the pores.

3. The method of preparing a substance containing a rare metallic oxidefor use in electrical appliances which consists in removing the occludedgases therefrom, sealing the pores with a liquefied solid, incorporatingthe same in the electrical appliance and then removin the seal from thepores.

4. The met 0d of preparing a substance containing a rare metallic oxidefor use in electrical appliances which consists in replacing theoccluded gases therein with a solid hydrocarbon, incorporating the samein the electrical appliance and removing the hydrocarbon.

5. The method of preparing a substance containing a rare metallic oxidefor use in electrical appliances, whichconsists in replacing theoccluded gases therein with .a

.solid hydrocarbon, incorporating the same in the electrical applianceand removing the hydrocarbon while the body is in a vacuum.

- aeeaaee .mersing the body in a bath of a solid hydrocarbon at thetemperature of boiling of the same until the occluded gases have beenreplaced by the liquid, allowing the liquid' to become solid,incorporating the re ared body in the electrical appliance, vo ati izingthe hydrocarbon and removing the vapors by exhaustion.

8. The method of forming a light source for incandescent electric lampsincluding a luminant composed of rare metallic oxides having associatedtherewith a heating element, which consists in immersin the luminant ina bath of boiling para e until the occluded gases have been replaced bythe parafline, allowing the parafline to solidify, associating theheating element withthe luminant, incorporating the light source in thebulb of. a lamp, exhausting the bulb, volatilizing the parafiine andremoving the vapors from the bulb.

9.- The method of forming a light source for incandescent electric lampsincluding a luminant of rare metallic oxides having as- I sociatedtherewith a heating element, which consists in immersing the luminant ina bath of boiling parafline until the occluded gases have been replacedby the parafiine, allowing the parafline to solidify, associating theheating element with the luminant, incorporating the light source inthe. bulb of a lamp, exhausting the bulb, volatilizin the parafline andremoving the vapors rom the bulb while the bulb is kept at a temperaturesu'flicient to prevent deposition of the parafiine thereon.

10. The method of preparing a body of rare metallic oxide for use inelectrical appliances which consists in introducing a material capableof being volatilized into the pores of the body, inserting the body inthe appliance and heating the electric appliance to remove the material.

11. The process of removing occluded solid and displace the 000 udedgases therein, 5

removing the body to a closed chamber, heating the chamber-until thematerial in the body is volatilized, and removing the volatilized gases.

12. A method of removing oxygen fro a fi body for use in electric lampswhich consists in replacing the oxygen withva solid and vaporizing thesolid in a vacuum.

13. A method of preparing a solid freed of occluded oxidizing gaseswhich consists in ap 1y heat to a solid to remove the gases, an repacing the gases with an inert vaporizagle soggdsupstance. 1 d t ed' fmet 0 re arin asoi re 0 ocdl iided p P g oxidizing gases for use inelectric.

apparatus which consists in removingthe' occluded gases in a solid bythe application of heat, replacing the gases with an inert vaporizablesolid substance and heating the solid-in a vacuum toremove the inertsubstance.

15. A method of removing occluded gases from solids which com risesimmersing the solid in a heated liquid bath of a vaporizable substancesolid at normal room temperatures,

permitting the substance to permeate the solid and displace the occludedgases allow-' ing the solid to cool and the substance to solidify,placing the body in a chamber subject to the evacuating action of asuction pump, and subjecting the body to heat while under evacuationwhereby the coating substance is vaporized and removed.

16. The method of preparing refractory oxides containing occluded gasesfor use under high tem erature conditions which consists in pow eringthe oxide, heating the oxide, to brin about dehydration, moulding thedehydrated oxide to the desired form, sintermg the oxide by theapplication of relatively high temperatures, heating the oxide in aliquid bath until the occluded gases are removed, permitting the liquidto permeate the oxide and displace the occluded gases therein, chillingvthe oxide to cause solidification of the liquid, placing the oxide inan evacuated chamber, heating the oxide within said chamber tovolatilize the solidified liquid, and removing the volatilized vapors bysuction apparatus.

JOHN ALLEN HEANY.

